Dual-fuel engines, such as those operating using diesel fuel and natural gas (or other pilot ignited gaseous fuel), are utilized in vehicles, in pumping applications, as well as other applications. Diesel fuel has a relatively constant and known composition that has a known and predictable energy content per unit of mass thereof. Natural gas, however, is comprised of multiple elements such as Methane, Ethane, Propane, Hexane, Pentane, Butane, and others. Not all of the constituent gasses are combustible. Even those components that are combustible have differing amounts of energy per unit mass thereof. Still further, when obtaining gas, it is unknown how much of the mass and/or volume thereof is combustible fuel. Accordingly, when obtaining natural gas, the amount of energy present in a unit mass is not immediately known.
Engines are produced having a load capacity (capacity for torque, power, or combinations thereof). Exceeding this load capacity subjects the engine and its constituent parts to premature failing and overall reduction in the expected life thereof. Fueling decisions (and other decisions) related to the engine are made with an attempt to keep the engine operating within its rated capacity.
When an engine is operating near capacity, an increase in energy provided to the engine (such as via a particularly fuel with high energy content per unit mass and/or volume) has the potential to cause the engine to operate above its rated capacity.
One solution to keep an engine operating below its capacity is to set the engine rating at an artificially low level such that any energy variability from the fuel is unable and/or very unlikely to send the engine above its design capacity. However, this prevents the engine from being fully utilized under normal fueling conditions.
What is therefore needed is a system for monitoring engine operation and determining the energy present in the fuel to allow the engine to take such energy determinations into account.